In the past in the context of downhole tools that employ expansion to seal an annular gap around its mandrel the degree of sealing contact of a resilient sleeve mounted to the mandrel with the surrounding wellbore could be controlled in two ways. One way was the degree of expansion from within the mandrel afforded by the swage being employed. Another way was to simply alter the thickness of the sleeve mounted to the mandrel. For a given borehole size, a thicker resilient sleeve resulted in a tighter seal of the sleeve against the surrounding borehole for a given amount of mandrel expansion with a swage. A given size pipe had limits on how much it could be expanded. On the other hand keeping many versions of a tool on a job site that have different thicknesses of resilient sleeves is impractical logistically and is very expensive. What is needed in an expandable tool is a way to activate the exterior member be it a seal in the form of a resilient sleeve or a porous member to be subsequently used for passing or filtering fluid. The present invention provides this opportunity. It employs the progressive expansion of the mandrel to move a ring into the exterior member to compress it and increase its outer dimension. The ring is capable of being locked to the mandrel after being moved by the swage that moves within the mandrel. The ring can expand so as to not put the swage in a bind while still having a capability to latch to the mandrel to prevent the exterior member from snapping back in length at the conclusion of the expansion.
The invention can be compared to known techniques one of which is illustrated in U.S. Pat. No. 6,530,574 where the mandrel is pushed in to accommodate a sealing material on the exterior of the mandrel. The swage is passed through the mandrel pushing out the interior projection that initially allowed the sealing material to sit flush with the mandrel exterior wall for run in. By returning the inner dimension of the mandrel back to a cylindrical shape the sealing material is pushed radially outwardly into contact with a surrounding tubular. Other known art keeps packer sealing elements from extrusion when they are squeezed longitudinally by a setting sleeve device. This tool, shown in U.S. Pat. No. 6,203,020 does not involve mandrel expansion. Yet other designs simply use mandrel expansion to engage a seal on the exterior of a casing patch with a surrounding wellbore tubular. Some examples of this design are U.S. Pat. No. 6,622,789 and U.S. Applications 2003/0102127 and 2004/0016544.
Those skilled in the art will better understand the invention from the description of the preferred embodiment, the drawings and the claim, all of which appear below.